1. Technical Field
The technical field generally relates to a liquid crystal display device, and particularly relates to a device and a method of driving a liquid crystal display device for display regions of differing brightness.
2. Discussion of the Related Art
Display devices may use cathode-ray tubes (CRT). Other flat panel displays, such as liquid crystal display (LCD) devices, plasma display panels (PDP), field emission displays, and electro-luminescence displays (ELD), exist as alternatives to the CRT. In particular, LCD devices have been widely used. LCD devices may provide several advantages, such as high resolution, light weight, thin profile, compact size, and low power supply requirements.
An LCD device may include two substrates that are spaced apart and face each other with a liquid crystal material interposed between the two substrates. The two substrates include electrodes that face each other such that a voltage applied between the electrodes induces an electric field across the liquid crystal material. The light transmissivity of the LCD device can be changed by adjusting the intensity of the induced electric field to change an alignment of the liquid crystal molecules in the liquid crystal material. Thus, the LCD device displays images by varying the intensity of the induced electric field.
FIG. 1 is a block diagram of an LCD device according to the related art.
As shown in FIG. 1, the LCD device may include a liquid crystal panel 190, a driving circuit 100 and a backlight unit 192.
The liquid crystal panel 190 includes a plurality of gate lines GL1 to GLn and a plurality of data lines DL1 to DLm (where n and m are natural numbers) crossing each other to define a plurality of pixel regions P. In each pixel region P, a thin film transistor T may be connected to the corresponding gate and data lines, and a liquid crystal capacitor Clc may be connected to the thin film transistor T.
The driving circuit 100 may include an interface 140, a timing controller 130, gate and data drivers 110 and 120 and an inverter 150.
The interface 140 may be supplied with data signals and control signals, such as a horizontal synchronization signal (Hsync), a vertical synchronization signal (Vsync), a data enable signal (DE) and a data clock (DCLK) from an external operating system 50 and may transfer such the signals to the timing controller 130.
The timing controller 130 generates control signals and data signals using the signals transferred from the interface 140.
The gate driver 110 may enable the gate lines GL1 to GLn according to the control signals supplied from the timing controller 130, and may enable the gate lines sequentially. The thin film transistors T connected to the enabled gate line may be turned on. The data driver 120 generates data voltages according to the control signals supplied from the timing controller 130 and outputs the data voltages to the data lines DL1 to DLm. The data voltages are supplied to the liquid crystal capacitors Clc connected to the enabled gate line.
The inverter 150 generates a backlight driving voltage from a DC voltage input thereto and outputs the backlight driving voltage to the backlight unit 192.
Although not shown in FIG. 1, the driving circuit further includes a power supplier supplying voltages to components of the LCD device and a gamma reference voltage generator supplying gamma reference voltages to the data driver 120.
Some computer display windows, for example, a window for displaying a high resolution image such as a moving image and a window for displaying a low resolution image such as a standing image (a word processor) may be displayed simultaneously in a screen of the liquid crystal panel for user's convenience. FIG. 3 example windows displayed simultaneously in the screen of the related art liquid crystal panel.
However, the related art LCD device may not normally display all windows in the screen. In other words, a user may perceive that a moving image is normally displayed when the moving image is bright and a word processor is normally displayed when the standing image is darker than the moving image. In this situation, brightnesses for the different displayed images may be different.
If the backlight unit supplies a light having a luminance suitable to display one of the windows, other windows requiring a different luminance may not be normally displayed. For example, if the backlight unit supplies light of about 300 nit, a user may perceive that the moving image is normally displayed but the standing image is abnormally displayed, such as too brightly. If the backlight unit supplies light of about 100 to 150 nit, a user may perceive that the standing image is normally displayed but the moving image is abnormally displayed, such as too darkly.